Try to get preferred external provider
Try to get preferred external provider

When using an opaque key, try to honor the system's preferred provider
which is selected via late binding. If it's not found, try to find the
first provider that initializes correctly with the given key.

(cherry picked from commit c590a930a5faff2563fdf4247eb694a243b71b96)

Bug: 21737886
Change-Id: I17483136aa5c1c5e474109525aefac9facaf7379

google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt